Carding machine and process for producing an aerodynamic card web

ABSTRACT

A card apparatus for producing an aerodynamically formed fibrous web (4), includes a fiber feed means (6), a main cylinder (8) rotating at high speed and a shaft (10) arranged at main cylinder (8), the shaft transporting thrown-off fibers in an airflow (12) to an air-permeable web transport means (14) and disposing said fibers on said web transport means (14) in the form of a fibrous web (4). In this apparatus the main cylinder (8) throws off said fibers at a first location (22) of shaft (10) onto a second cylinder (20) rotating at high speed in opposite sense to main cylinder (8) and generating a random orientation of said fibers on cylinder (20), and the second cylinder (20) throws off said fibers into airflow (12) at a second location (24) of shaft (10).

BACKGROUND OF THE INVENTION

The invention refers to a card for making an aerodynamically formedfibrous web.

Such cards are known, for example, from U.S. Pat. No. 3,256,569, U.S.Pat. No. 4,064,600, U.S. Pat. No. 4,097,965, U.S. Pat. No. 4,130,915 andDE 39 01 313 A.

In known cards, after an opening and carding process, the fibers arethrown off from a main cylinder into an airflow. This airflow transportsthe fibers to a screen means, e.g. a screen drum or a screen band, onwhich the formation of the web takes place and from which a fibrous webmay be doffed continuously.

Starting from prior art as of DE 39 01 313 A, it is the object of theinvention to provide a card which allows for a better uniformity of thefibrous web, in particular with lighter webs, while offering highproduction rates.

The object is solved, according to the invention, with the features ofclaims 1 and 8.

SUMMARY OF THE INVENTION

Advantageously, the invention provides to employ another cylinderrotating in opposite sense with respect to the main cylinder, whichfirst receives fibers thrown off from the main cylinder and then throwsthem off into a shaft. This structure is of particular importance whenusing fiber mixtures with greatly different values with regard to thefineness, fiber density and fiber length. The second cylinder leads toan improved homogeneity and a better random orientation of the laid web.The main cylinder and the cylinder rotating in opposite sense thereto donot contact each other. Both radii of the fittings are also at adistance from each other. The method of the invention is particularlysuitable for producing lighter fibrous webs at a very high productionrate.

Preferably, the peripheral speed of the second cylinder is betweenapproximately 80 and 110% of the peripheral speed of the main cylinder.Due to the almost equal peripheral speed of the second cylinder, acombing of the fibers is reliably prevented. The fibers are thrown fromthe main cylinder and laid on the second drum in random orientation.Without further combing operations, these fibers are transported intothe shaft, again, by centrifugal forces, the shaft being flown throughsubstantially by the peripheral air of the two drums rotating therewith.

The fiber feed means may at the same time form a preliminary fiberopening means. Thus, a preliminary opening of the fibers is obtained.

In a preferred embodiment it is provided that a carding section isprovided between the fiber feed means and the main cylinder, comprisinga plurality of successive carding rolls with working rolls. The cardingsection causes a particularly good opening of the fibers.

In the peripheral portion containing the fibers, the main cylinder iscovered with trough covers or carding elements, so that the fibers leavethe main cylinder at a defined location by centrifugal force.

The airflow forming in the shaft is substantially constituted by theentrained air of the main cylinder and of the second cylinder.

The following is a detailed description of embodiments of the invention,taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of the invention with an upstreamcarding section,

FIG. 2 shows a second embodiment with a cylinder at the beginning of thecarding section, and

FIG. 3 shows a third embodiment without a carding section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The card of FIG. 1 comprises a non-illustrated machine frameaccommodating a carding section 28, a main cylinder 8, a second cylinder20, as well as a shaft 10 beginning between the main cylinder 8 and thesecond cylinder 20.

The carding section 28 has five successively arranged carding rolls 31to 35 to which five working rolls 36 to 40 are associated. The spinningmaterial or the supply web is fed by the fiber feed means 6 comprising afeed roll with a feeding trough. At the end of the carding section 28,the web present on the last carding roll 35 is taken over by the maincylinder 8.

From carding roll to carding roll, in the direction of the operationprogress, there is provided an increase in the roll speed together witha systematic gradation of the respective fittings, thus obtaining a highcarding effect for a progressive fiber isolation.

The rolls of the carding section 28, the lower working rolls 39,40 andthe main cylinder 8 may be covered by trough plates 11.

On the upper side, the main cylinder 8 is covered by trough covers 9.The main cylinder 8 has a diameter of about 550 mm. The preferredperipheral speed of the main cylinder 8 ranges between 2,800 and 4,300m/min. At the last trough cover 9 in the peripheral direction of themain cylinder 8, the extremely fine-opened fibers are loosened from thefitting of the main cylinder 8 in an explosion-like manner, due to thecentrifugal forces acting on the fibers, and the fibers are thrown ontothe second cylinder 20, where they are caught in an optimum random fiberorientation.

The second cylinder 20 rotates at about the same peripheral speed as themain cylinder 8, whereby it is reliably prevented that fibers are combedinto the second cylinder 20. The peripheral speed of the cylinder 20 isabout 80 to 110% of the peripheral speed of the main cylinder 8. Theradii of the fittings of the cylinders 8, 20 do not contact each other.

The second cylinder 20 may have the same diameter as the main cylinder8, or as represented in the drawings, it may have a smaller diameterabout the size of the last carding roll 35 of the carding section 28,i.e. about 400 mm in diameter.

The second cylinder 20 has a lower trough segment 19 and an upper troughcover 18. The airflow 12 forming in the shaft 10 may be formedexclusively by the air entrained by the cylinder peripheries of thecylinders 8, 20. Additional air 23 may be taken in between the troughcovers 9 and 18. The loosening of the fibers from the fittings of thecylinders 8, 20 is regulated by variably adjustable peripheral speedsand air velocities in dependence on the breast angle of the fittings andthe fiber specifications.

Due to the high peripheral speed of the second cylinder 20 and afteronly a very short stay on the cylinder 20, the fibers are immediatelythrown tangentially into the shaft 10, where they are transported in anairflow 12 to a fiber transport means 14 on which the fibers aredeposited and a fibrous web 4 is produced that can be doffedcontinuously by means of an air-permeable conveyor belt 17 of the webtransport means 14.

The air-permeable conveyor belt 17 is continuous and is deflected bydeflection rollers 21 so that a section extends transversal to theairflow 12 at the end of the shaft 10. Disposing the fibers on theconveyor band 17 is assisted by a suction airflow 16. Above the conveyorbelt 17, a pressure roll 25 for compacting the fibrous web 4 is arrangedbeside the shaft 10 in the doffing direction of the fibrous web 4.

The suction air flow is generated in a suction shaft 15 of the webtransport means 14 extending beneath the conveyor belt 17.

The trough covers 9 in the embodiments of FIGS. 1 and 2 may be replacedwith carding elements 42.

The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in that ashorter carding section 28 is provided upstream of the main cylinder 8.

This carding section 28 has but three carding rolls 33, 34, 35, upstreamof which a cylinder 44 with a pair of working and stripping rolls 29 isarranged.

Initially, a fiber feed means 6 supplies the fibrous web by means of afeed roll and a feeding trough of the drum 44. Between the drum 44 andthe first carding roll 33, an upper working roll 37 and a lower workingroll 38 are provided. A further working roll 39 is arranged above andbetween the first and the second carding roll 33, 34.

FIG. 3 illustrates an embodiment without a carding section, wherein apreliminary fiber opening means 6 serves as the fiber feed means at thesame time. Using a roll 26 and a trough 27 of the preliminary fiberopening means 6, the supply web is preliminarily opened and transferreddirectly onto the main cylinder 8. In this embodiment, it is providedthat carding elements 42, instead of trough covers 9, are arranged onthe circumference of the main cylinder 8 between the fiber feed locationat the roll 26 and the fiber discharge location 22 at the shaft 10. Thecarding elements 42 in the form of cardmaster plates can fine-open thepreliminarily opened web into individual fibers before it is thrown offat the discharge location 22 tangentially but transversal to the shaft10 in towards the second cylinder 20 spaced from the main cylinder 8.The fibers reach the second cylinder 20, serving as a catching means, inan optimum random orientation and are thrown off tangentially into theair flow 12 after a short stay on the cylinder 20 at the location 24, inorder to be deposited onto the conveyor belt 17 of the web transportmeans 14 with a high uniformity in fiber distribution and in theaccumulating web thickness.

As an alternative, an additional airflow 23 may be drawn between thelast carding element 42, seen in the transversal direction of the maincylinder 8, and the trough cover 18.

Again, in this embodiment, the shaft 10 may be closed or sealed at itstop end so that the airflow 12 is constituted only by the peripheral airof the cylinders 8, 20.

It is claimed:
 1. A card apparatus for producing an aerodynamicallyformed fibrous web, the apparatus including a fiber feed means, a maincylinder rotating at high speed, and a shaft situated adjacent said maincylinder, said shaft transporting thrown-off fibers in an air flowflowing downstream to an air-permeable web transport means and disposingof said fibers on said web transport means in the form of a fibrous web,the improvement comprising a second cylinder parallel and adjacent themain cylinder and rotating at high speed in opposite sense to said maincylinder, where said main cylinder throws off said fibers at a firstlocation into said shaft and thence onto said second cylinder generatinga random orientation of said fibers on said second cylinder, and saidsecond cylinder throws off by centrifugal forces said fibers which havebeen rotated circumferentially from said first location into saidairflow at a second location of said shaft spaced downstream from saidfirst location and thence out.
 2. The card of claim 1, characterized inthat the peripheral speed of said second cylinder ranges between 80 and110% of the peripheral speed of the main cylinder.
 3. An apparatusaccording to claim 2 wherein said main and second cylinders haveperipheral speed substantially the same.
 4. The card of claim 1,characterized in that said fiber feed means at the same time is apreliminary fiber opening means.
 5. The card of claim 1, characterizedin that a carding section with a plurality of successively arrangedcarding rolls is provided between said fiber feed means and said maincylinder.
 6. The card of claim 5, characterized in that in said cardingsection, a drum with at least one pair of working and stripping rolls isarranged upstream of said carding rolls.
 7. The card of claim 1,characterized in that said main cylinder has carding elements.
 8. Thecard of claim 1, characterized in that said shaft is open at the topend.
 9. The card of claim 2, characterized in that said fiber feed meansat the same time is a preliminary fiber opening means.
 10. A method forproducing an aerodynamically formed fibrous web by feeding fibers to anopening means (18), feeding the opened fibers to a main cylinder (8)rotating at high speed, throwing the fibers off said cylinder (8) onto asecond cylinder (20) rotating at high speed in opposite sense to saidmain cylinder (8) and transversal to an airflow (12) entrained betweensaid cylinders (8, 20), subsequently throwing said fibers off saidsecond cylinder (20) tangentially into said airflow (12) and depositingsaid fibers on an air-permeable web transport means (14) to form a web(4).
 11. The method of claim 10, characterized in that said fibers passa carding section (28) before being fed to said main cylinder (8), wherethey are carded several times.
 12. A card apparatus according to claim 1wherein said airflow is entrained between adjacent peripheral surfacesof said main and second cylinders and where said second cylinder throwsoff said fibers in a tangential direction relative to its peripheralsurface.
 13. The method of one of claims 10 or 11, characterized in thatsaid fibers are carded immediately before being thrown off said maincylinder (8).
 14. The method of one of claims 10 to 11, characterized inthat the peripheral speed of said cylinder (20) is set to a valuebetween about 80 and 110% of the peripheral speed of said main cylinder(8).
 15. The method of claim 13, characterized in that the peripheralspeed of said cylinder is set to a value between about 80 and 110% ofthe peripheral speed of said main cylinder.
 16. The method of claim 11,characterized in that the peripheral speed of said cylinder is set to avalue between about 80 and 110% of the peripheral speed of said maincylinder.